C++ By Example: UnderC Learning Edition

Defensive Programming

There are five desirable properties of good programs: They should be robust, correct, maintainable, friendly, and efficient. Obviously, these properties can be prioritized in different orders, but generally, efficiency is less important than correctness; it is nearly always possible to optimize a well-designed program, whereas badly written ”lean and mean” code is often a disaster. (Donald Knuth, the algorithms guru, says that “premature optimization is the root of all evil.”)

Here I am mostly talking about programs that have to be used by non-expert users. (You can forgive programs you write for your own purposes when they behave badly: For example, many scientific number-crunching programs are like bad-tempered sports ...